List ItemUpdating - AfterProperties allways empty

Hi,

I'm traying to validate a listItem update on a receiver ItemUpdating event.

I'm trying to validade de new value watching for properties.AfterProperties["column"], but it is allways null.

I can´t use properties.ListItem["column"] because it has the "old" value, not the new one.

How can I do it?

Many Thanks,

DD